As cloud computing is becoming more popular, communication traffic in data centers is increasing. Accordingly, the speedup of interfaces accommodating huge communication traffic has been desired. Optical path setup technologies for interconnecting servers via optical links have been developed for data centers and so on.
As one optical interconnect technology, an optical communication network for interconnecting a plurality of communication nodes has been proposed. The optical communication network includes an arrayed waveguide grating (AWG). The AWG has N input ports and N output ports and has a routing function for guiding input light to a corresponding output port according to a wavelength of the input light. M (M is smaller than or equal to N) communication node equipments are connected to the AWG via optical transmission lines. To dynamically change a logical network topology representing the geometry of the path of signal light used for data transmission and reception between the communication node equipments, each of the communication node equipments includes wavelength switching means for switching the wavelength of the signal light. (For example, WO 2004/073225)
As a related art, Japanese Laid-open Patent Publication No. 2001-60922 describes a network interconnecting a plurality of nodes using a WDM system and an AWG. Japanese Laid-open Patent Publication No. 2002-101432 describes an optical switch network and an optical crossconnect.
In an optical network in which a plurality of node equipments are connected in a star configuration by an AWG, it is preferable that the node equipments be one-hop connected to enhance the efficiency of the data transmission between the node equipments. To one-hop connect optional node equipments to each other, it is logically necessary to adopt a full mesh topology.
To achieve such a network, however, each node equipment needs to include many optical devices. As an example, to connect N node equipments in a full mesh topology by using an N×N AWG, each node equipment needs to include N−1 transmitters for transmitting N−1 different wavelengths and N−1 receivers for receiving the N−1 wavelengths.
As described above, in the prior art, a transceiver of each node needs to include many optical devices to enhance the efficiency of the data transmission between the node equipments. Accordingly, the power consumption of a node equipment increases. The size of a transceiver increases and cost of the transceiver also increases.